1. Field of the Invention
The present invention relates to a three-dimensional structure transfer method and apparatus, and more particularly to a three-dimensional structure transfer method and apparatus for manufacturing a substrate having a three-dimensional structure such as a barrier rib in a display region between a glass substrate on the front face side and a glass substrate on the back face side as in a plasma display panel (PDP), for example.
2. Description of the Related Art
As an example of the substrate having a three-dimensional structure, a PDP substrate having a barrier rib will be described below. The PDP is a display panel of a self-luminous type in which a pair of substrates (usually, glass substrates) are opposed to each other with a very small space and the surroundings are sealed to form a discharge space therein.
In general, the PDP has a barrier rib (three-dimensional structure) having a height of approximately 100 to 200 xcexcm provided periodically to partition a discharge space. For example, in a surface discharge type PDP suitable for color display using a phosphor, a barrier rib which is rectilinear or grid-shaped as seen in a plane is provided on a substrate having data electrodes (address electrodes) arranged thereon. The barrier rib prevents the interference of discharge and the crosstalk of colors.
A method of fabricating the PDP substrate having the above-mentioned structure generally comprises a process for forming data electrode pattern on a glass substrate and forming a barrier ribs to make alignment with the electrode pattern. Various methods of forming barrier ribs have been proposed and carried out. Typical examples of the forming methods include a screen printing method of repeating screen printing to print laminated barrier ribs, a sand blasting method of spraying blast particles to carry out cutting, an embedding method of embedding a barrier rib material in the concave portion of a photosensitive material layer and removing the photosensitive material layer, a photolithographic method using a photosensitive material for barrier ribs and a transfer method of transferring barrier ribs onto a substrate by using a mother die for transfer (mold). In particular, attention has been paid to the transfer method which can be implemented at the lowest cost.
In the transfer method, a mold provided with trenches or concaves for forming barrier ribs is used. In the procedure, the concaves of the mold is filled with a barrier rib material and is then transferred onto a substrate so that barrier ribs are formed.
Various techniques have been proposed for transferring a barrier rib material in the transfer method. For example, Japanese Laid-Open Patent Publication No. Hei 9(1997)-134676 has described a method of filling an intaglio with a barrier rib material and then transferring the barrier rib material onto a substrate through heat press. However, in the case in which a heat treatment is to be carried out, it is necessary to consider expansion of the intaglio, barrier rib material and a substrate and the like. In particular, when crossing three-dimensional structure patterns are to be superposed, a very complicated calculation is required. In order to eliminate this drawback, it is desirable that transfer should be carried out at room temperature in principle.
As a method of removing the mold for the transfer method, there have been known a planographic transfer and removal (the whole pattern is transferred and then the mold is removed) method of carrying out transfer with a planar mold and removing the planar mold while keeping its nearly planar shape and a curved transfer (removal is carried out immediately after transfer) method using a roller for carrying out removal while performing transfer with a curved mold provided along a roller face.
Examples of transfer techniques used for the transfer method which are carried out at a room temperature include an adhesion transfer technique using an adherent material as described in Japanese Laid-Open Patent Publication No. Hei 10(1998)-326560. In the adhesion transfer method, the transfer can be carried out at room temperature. Therefore, there is an advantage that transfer can be implemented with high dimensional precision.
However, in the case in which a barrier rib is to be transferred by the planographic transfer and removing method using the above-mentioned technique, it is necessary to maintain a substrate and a mold in parallel with each other in order to align electrodes formed on the substrate with barrier ribs to be transferred and formed. Therefore, the mold should necessarily be removed vertically from the substrate after the transfer. For this reason, considerable force is required for the removal of the mold. If the adhesion strength between a transfer material and the substrate and the strength of the transfer material itself are not sufficiently great, a structure to be transferred is broken during the transfer or the transfer cannot be carried out.
In the case in which the barrier ribs are to be transferred by the curved transfer method using the above adhesion transfer technique, it is necessary to fixedly wind up the mold around a roller, thereby carrying out the transfer and the removal at the same time. Therefore, if the adherent strength between the transfer material and the substrate is not sufficiently greater than that between the mold and the transfer material, an object to be transferred is wrinkled or the roller is stopped. This problem becomes much greater obstruction as an area to be transferred is increased.
In consideration of these circumstances, it is an object of the present invention to provide a three-dimensional structure transfer method and apparatus in which a sheet-form mold is temporarily fixed to a support member and the support member is utilized to contact-bond a structural material (transfer material) to the substrate together with the mold and then release the temporary fixation and peel the sheet-form mold from the substrate so that transfer can be carried out smoothly with high precision without a great influence by the adhesion strength and removing property of the structural material.
The present invention provides a method for a three-dimensional structure transfer method for transferring a three-dimensional structure onto a substrate, comprising the steps of: preparing a paste-like structural material which can exert an adhesion property or a bonding property after curing or semi-curing, filling a plurality of concaves arranged on a sheet-form mold with the paste-like structural material, and curing or semi-curing the paste-like structural material; temporarily fixing the mold to a support member; aligning the mold and a substrate and then contact-bonding the structural material in a state in which the structural material has the adhesion property or bonding property to the substrate together with the mold; releasing the temporary fixation of the mold by the support member after the contact-bonding; and removing the mold from the substrate, thereby transferring a three-dimensional structure onto the substrate.
In the present invention, after the sheet-form mold filled or coated with the structural material is temporarily fixed to the support member, the alignment of the relative positions of the mold and the substrate is carried out and the structural material is contact-bonded to the substrate together with the mold, and the mold is released from the support member through the release of the temporary fixation and the sheet-form mold is then peeled off the substrate. Thus, the three-dimensional structure is transferred and formed on the substrate.
According to the present invention, the transfer step is divided into two steps, that is, a contact-bonding (sticking) step and a removing step. At the removing step, it is possible to carry out the peeling which requires the least excessive force to be applied to the removal. Therefore, it is possible to greatly relieve limitations on the adhesion strength and mechanical strength of the structural material and the degree of the removing property of the mold. Thus, the three-dimensional structure can be transferred and formed with high precision in a large area.